PIV3 causes bronchiolitis and pneumonia in infants. Currently, no satisfactory vaccine is available for its prevention. The long term objective of this application is to apply a novel adjuvant to the production of an effective, safe vaccine against PIV3. The proposed adjuvant is a proprietary formulation of microcrystalline cellulose, starch, and sugar. The investigators propose to use a hamster model to test the ability of the novel adjuvant to enhance the immune response to PIV3.In the Phase I trial, octylglucoside soluble envelope proteins of PIV3 will be used as the vaccine antigen. The efficacy of the vaccine preparation will be tested by analyzing serum and bronchial samples from immunized animals in virus specific ELISA and virus neutralization studies to determine the magnitude and type of the immune response and by determining titers of virus in the lung after challenge with live virus. Subcutaneous, intramuscular, intraperitoneal, oral, and intranasal routes of immunization will be compared to determine the most effective immunization protocol. In subsequent studies, the efficacy of the adjuvant used in combination with subunit PIV3 vaccines and recombinant parainfluenza vaccine will be explored.